Operational-based compensation of a power amplifier

ABSTRACT

A method for compensating a power amplifier based on operational-based changes begins by measuring one of a plurality of operational parameters of the power amplifier to produce a measured operational parameter. The method continues by comparing the measured operational parameter with a corresponding one of a plurality of desired operational parameter settings. The method continues by, when the comparing of the measured operational parameter with the corresponding one of a plurality of desired operational parameter settings is unfavorable, determining a difference between the measured operational parameter and the corresponding one of a plurality of desired operational parameter settings. The method continues by calibrating the one of the plurality of operational settings based on the difference.

This patent application is claiming priority under 35 USC § 120 as acontinuing patent application of co-pending patent application entitledCOMPENSATING A POWER AMPLIFIER BASED ON OPERATIONAL-BASED CHANGES,having a filing date of Apr. 30, 2004, and a Ser. No. 10/836,873.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to wireless communication systems andmore particularly to power amplifiers of wireless transmitters.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel(s). For indirect wirelesscommunications, each wireless communication device communicates directlywith an associated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe Internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the receiver is coupled to theantenna and includes a low noise amplifier, one or more intermediatefrequency stages, a filtering stage, and a data recovery stage. The lownoise amplifier receives inbound RF signals via the antenna andamplifies then. The one or more intermediate frequency stages mix theamplified RF signals with one or more local oscillations to convert theamplified RF signal into baseband signals or intermediate frequency (IF)signals. The filtering stage filters the baseband signals or the IFsignals to attenuate unwanted out of band signals to produce filteredsignals. The data recovery stage recovers raw data from the filteredsignals in accordance with the particular wireless communicationstandard.

As is also known, the transmitter includes a data modulation stage, oneor more intermediate frequency stages, and a power amplifier. The datamodulation stage converts raw data into baseband signals in accordancewith a particular wireless communication standard. The one or moreintermediate frequency stages mix the baseband signals with one or morelocal oscillations to produce RF signals. The power amplifier amplifiesthe RF signals prior to transmission via an antenna.

As is further known, it is desirable for the power amplifier to belinear over its operating range (i.e., have the same amplificationproperties over temperature, process variation, and transmit powerlevels). To achieve linearity of the power amplifier, it has beendesigned based on worst case operating conditions. While this achievesthe goal of a linear power amplifier, typically, the power amplifier isover-designed. As a result of being over-designed, the power amplifierrequires more current to function and thus consumes more power than istypically required. Such an increase in power consumption results in anincrease in die area and cost.

Therefore, a need exists for an adjustable power amplifier having itsoperation at least partially dependent on operational conditions suchthat the adjustable power amplifier consumes less power.

BRIEF SUMMARY OF THE INVENTION

The compensating of a power amplifier based on operational based changesof the present invention substantially meets these needs and others. Inone embodiment, a method for compensating a power amplifier based onoperational-based changes begins by measuring one of a plurality ofoperational parameters of the power amplifier to produce a measuredoperational parameter. The method continues by comparing the measuredoperational parameter with a corresponding one of a plurality of desiredoperational parameter settings. The method continues by, when thecomparing of the measured operational parameter with the correspondingone of a plurality of desired operational parameter settings isunfavorable, determining a difference between the measured operationalparameter and the corresponding one of a plurality of desiredoperational parameter settings. The method continues by calibrating theone of the plurality of operational settings based on the difference.

In another embodiment, an adjustable power amplifier includes anadjustable input capacitor section, an adjustable input transistorsection, an inductor, an adjustable bias voltage circuit, and acalibration module. The adjustable input capacitor section includes aninput connection, an output connection, and a ground connection, whereinthe input connection of the adjustable input capacitor section isoperably coupled to receive an input radio frequency (RF) signal and theground connection of the adjustable input capacitor section is operablycoupled to a circuit ground. The adjustable input transistor sectionincludes an input connection, an output connection, and a sourceconnection, wherein the input connection of the adjustable inputtransistor second is operably coupled to the output connection of theadjustable input capacitor section and the source connection of theadjustable input transistor section is operably coupled to the circuitground. The inductor includes a first node and a second node, whereinthe first node of the inductor is operably coupled to a power supply andthe second node of the inductor is operably coupled to the outputconnection of the adjustable input transistor section to provide anoutput of the adjustable power amplifier. The adjustable bias voltagecircuit is operably coupled to provide a bias voltage to the inputconnection of the adjustable input transistor section. The calibrationmodule is operably coupled to: measure one of a plurality of operationalparameters of the power amplifier to produce a measured operationalparameter; compare the measured operational parameter with acorresponding one of a plurality of desired operational parametersettings; when the comparing of the measured operational parameter withthe corresponding one of a plurality of desired operational parametersettings is unfavorable, determine a difference between the measuredoperational parameter and the corresponding one of a plurality ofdesired operational parameter settings; and calibrate at least one ofthe adjustable input capacitor section, the adjustable input transistorsection, and the adjustable bias voltage circuit based on thedifference.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a wireless communication systemin accordance with the present invention;

FIG. 2 is a schematic block diagram of a wireless communication devicein accordance with the present invention;

FIG. 3 is a schematic block diagram of an adjustable power amplifier inaccordance with the present invention;

FIG. 4 is a schematic block diagram of another adjustable poweramplifier in accordance with the present invention;

FIG. 5 is a schematic block diagram of yet another adjustable poweramplifier in accordance with the present invention;

FIG. 6 is a schematic block diagram of a still another adjustable poweramplifier in accordance with the present invention;

FIG. 7 is a schematic block diagram of even another adjustable poweramplifier in accordance with the present invention;

FIG. 8 is a logic diagram of a method for compensation a power amplifierbased on operational based changes in accordance with the presentinvention;

FIG. 9 is a logic diagram of a method for compensation a power amplifierbased on a particular operational condition in accordance with thepresent invention;

FIG. 10 is a logic diagram of a method for compensation a poweramplifier based on another particular operational condition inaccordance with the present invention; and

FIG. 11 is a logic diagram of a method for compensation a poweramplifier based on yet another particular operational condition inaccordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram illustrating a communication system10 that includes a plurality of base stations and/or access points12-16, a plurality of wireless communication devices 18-32 and a networkhardware component 34. The wireless communication devices 18-32 may belaptop host computers 18 and 26, personal digital assistant hosts 20 and30, personal computer hosts 24 and 32 and/or cellular telephone hosts 22and 28. The details of the wireless communication devices will bedescribed in greater detail with reference to FIG. 2.

The base stations or access points 12-16 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12-16 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 12-14 to receive services from the communication system10. For direct connections (i.e., point-to-point communications),wireless communication devices communicate directly via an allocatedchannel.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18-32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component.

As illustrated, the host device 18-32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, digital receiver processingmodule 64, an analog-to-digital converter 66, a filtering/gain module68, an IF mixing down conversion stage 70, a receiver filter 71, a lownoise amplifier 72, a transmitter/receiver switch 73, a localoscillation module 74, memory 75, a digital transmitter processingmodule 76, a digital-to-analog converter 78, a filtering/gain module 80,an IF mixing up conversion stage 82, a power amplifier 84, a transmitterfilter module 85, and an antenna 86. The antenna 86 may be a singleantenna that is shared by the transmit and receive paths as regulated bythe Tx/Rx switch 73, or may include separate antennas for the transmitpath and receive path. The antenna implementation will depend on theparticular standard to which the wireless communication device iscompliant.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in memory 75, execute digital receiver functions and digitaltransmitter functions, respectively. The digital receiver functionsinclude, but are not limited to, digital intermediate frequency tobaseband conversion, demodulation, constellation demapping, decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules 64 and 76 may be implemented using ashared processing device, individual processing devices, or a pluralityof processing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on operational instructions. The memory 75 may be asingle memory device or a plurality of memory devices. Such a memorydevice may be a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, and/orany device that stores digital information. Note that when theprocessing module 64 and/or 76 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE 802.11 Bluetooth, et cetera) toproduce digital transmission formatted data 96. The digital transmissionformatted data 96 will be a digital base-band signal or a digital low IFsignal, where the low IF typically will be in the frequency range of onehundred kilohertz to a few megahertz.

The digital-to-analog converter 78 converts the digital transmissionformatted data 96 from the digital domain to the analog domain. Thefiltering/gain module 80 filters and/or adjusts the gain of the analogsignal prior to providing it to the IF mixing stage 82. The IF mixingstage 82 converts the analog baseband or low IF signal into an RF signalbased on a transmitter local oscillation 83 provided by localoscillation module 74. The power amplifier 84, which will be describedin greater detail with reference to FIGS. 3-11, amplifies the RF signalto produce outbound RF signal 98. The transmitter filter module 85filters the outbound RF signal 98 before the antenna 86 transmits it toa targeted device such as a base station, an access point and/or anotherwireless communication device.

The radio 60 also receives an inbound RF signal 88 via the antenna 86,which was transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignal 88 to the receiver filter module 71 via the Tx/Rx switch 73,where the Rx filter 71 bandpass filters the inbound RF signal 88. The Rxfilter 71 provides the filtered RF signal to low noise amplifier 72,which amplifies the signal 88 to produce an amplified inbound RF signal.The low noise amplifier 72 provides the amplified inbound RF signal tothe IF mixing module 70, which directly converts the amplified inboundRF signal into an inbound low IF signal or baseband signal based on areceiver local oscillation 81 provided by local oscillation module 74.The down conversion module 70 provides the inbound low IF signal orbaseband signal to the filtering/gain module 68. The filtering/gainmodule 68 filters and/or gains the inbound low IF signal or the inboundbaseband signal to produce a filtered inbound signal.

The analog-to-digital converter 66 converts the filtered inbound signalfrom the analog domain to the digital domain to produce digitalreception formatted data 90. The digital receiver processing module 64decodes, descrambles, demaps, and/or demodulates the digital receptionformatted data 90 to recapture inbound data 92 in accordance with theparticular wireless communication standard being implemented by radio60. The host interface 62 provides the recaptured inbound data 92 to thehost device 18-32 via the radio interface 54.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 2 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the digital receiver processing module 64, thedigital transmitter processing module 76 and memory 75 may beimplemented on a second integrated circuit, and the remaining componentsof the radio 60, less the antenna 86, may be implemented on a thirdintegrated circuit. As an alternate example, the radio 60 may beimplemented on a single integrated circuit. As yet another example, theprocessing module 50 of the host device and the digital receiver andtransmitter processing modules 64 and 76 may be a common processingdevice implemented on a single integrated circuit. Further, the memory52 and memory 75 may be implemented on a single integrated circuitand/or on the same integrated circuit as the common processing modulesof processing module 50 and the digital receiver and transmitterprocessing module 64 and 76.

FIG. 3 is a schematic block diagram of an adjustable power amplifier 84that includes an input capacitor (C_(IN)), an adjustable gain module100, an input transistor (T_(IN)), an inductor (L₁), and an outputcapacitor (C_(OUT)). The power amplifier 84 is illustrated as asingle-ended amplifier but could be readily modified to be adifferential power amplifier by including a mirror image of thecircuitry of the power amplifier 84 of FIG. 3.

As configured, the input capacitor C_(IN) provides AC coupling of the RFinput signal to the gate of the input transistor T_(IN). The gain adjustmodule 100, based on an operational based control signal 102, adjuststhe AC coupled RF signal to maintain linearization of the poweramplifier 84. In one embodiment, the gain adjust module 100 is avariable capacitor that provides one of a plurality of capacitancevalues in response to a corresponding one of a plurality of values ofoperational based control signals. The operational based control signalsmay be determined based on at least one of process variations,temperature variations and/or output power variations. The determinationof such operational based control signals will be further described withreference to FIGS. 7-11.

The input transistor T_(IN) amplifies the adjusted input RF signal andproduces an output of the power amplifier in conjunction with theinductor L₁ and the output capacitor C_(OUT). The component values ofthe input capacitor, the input transistor, the inductor, and the outputcapacitor are dependent on the desired output power level of the poweramplifier and on the frequency range of the RF input signals. In oneembodiment, the frequency of the RF input signals may be in the 2.4 GHzrange and/or the 5 GHz range, where the inductance of the inductor L₁may range from fractions of nano Henries to tens of nano Henries, andthe capacitance of the input capacitor and output capacitor may rangefrom fractions of pico-Farads to tens of pico-Farads.

FIG. 4 is a schematic block diagram of another adjustable poweramplifier 84. In this embodiment, the adjustable power amplifier 84includes the input capacitor C_(IN), the input transistor T_(IN), theinductor L₁, the output capacitor C_(OUT), and a gain adjust module 104.The power amplifier 84 is illustrated as a single-ended amplifier butcould be readily modified to be a differential power amplifier byincluding a mirror image of the circuitry of the power amplifier 84 ofFIG. 4.

As configured, the input capacitor C_(IN) AC couples the RF inputsignals to the gate of the input transistor T_(IN) without attenuationas in the embodiment of FIG. 3. The input transistor T_(IN) amplifiesthe AC coupled RF input signals based on the inductance of the inductorL1 and on a setting of the gain adjust module 104. The amplified RFsignals are AC coupled via the output capacitor C_(OUT) to provide anoutput of the power amplifier 84. In one embodiment, the adjustable gainmodule 104 may be a variable capacitor circuit that provides one of aplurality of capacitance values in response to a corresponding one of aplurality of values of the operational based control signal. Theoperational based control signal may be determined from at least one ofprocessed variations, temperature variations and output powervariations. The determination of the operational based control signalwill be described in greater detail with reference to FIGS. 7-11.

FIG. 5 is a schematic block diagram of another embodiment of anadjustable power amplifier 84. The power amplifier 84 is illustrated asa single-ended amplifier but could be readily modified to be adifferential power amplifier by including a mirror image of thecircuitry of the power amplifier 84 of FIG. 5.

In this embodiment, the power amplifier 84 includes the input capacitorC_(IN), the input transistor T_(IN), the inductor L1, and the outputcapacitor C_(OUT), and an adjustable bias circuit 106. The inputcapacitor C_(IN) AC couples the input RF signals to the input transistorT_(IN). The adjustable bias circuit 106 adjusts the bias level of theinput transistor based on an operational based control signal 102 tomaintain linearity of the power amplifier as output power levelrequirements change, the operating temperature changes, and/or processvariations of the components of the power amplifier 84. The operationalbased control signal 102 will be further described with reference toFIGS. 7-11.

The input transistor T_(IN) in combination with the inductor L1 amplifythe AC coupled input RF signals to produce amplified RF signals. Theoutput capacitor C_(OUT) AC couples the amplified RF signals to providean output of the power amplifier 84.

As one of average skill in the art will appreciate, a power amplifiermay be constructed to include one or more of the adjustable bias circuit106, the gain adjust module 100, and/or the gain adjust module 104. Asone of average skill in the art will further appreciate, the componentsizes of the power amplifiers of FIGS. 3-7 may be in accordance with theexample provided with the discussion of FIG. 3.

FIG. 6 is a schematic block diagram of yet another embodiment of anadjustable power amplifier 84. In this embodiment, the power amplifier84 is a differential circuit and includes two input capacitors (C_(INN)and C_(INP)), two input transistors (T_(INN) and T_(INP)), two inductors(L_(N) and L_(P)), two output capacitors (C_(OUTP) and C_(OUTN)), twoinput variable capacitors 100 _(N) and 100 _(T), two output adjustablecapacitors 100 _(N) and 104 _(P) and a bias adjust circuit 106. The biasadjust circuit 106 includes a dependent current source and a transistorT₁.

In operation, the input capacitors receive differential input RFsignals. The variable capacitors 100N and 100P divide the voltage levelof the differential input RF signals based on the capacitance level setby the operational based control signal 102 with respect to thecapacitance of the input capacitors. The capacitor divided differentialinput RF signals are provided to the gates of the input transistors.

The bias circuit 106 establishes the bias voltage for the inputtransistors based on operational changes (e.g., temperature variations,power requirement changes, and/or process variations) by receiving theoperational based control signal 102 vias the dependent current source.The dependent current source produces a corresponding current that isprovided to transistor T1. As coupled, transistor T1 produces areference bias voltage that is coupled to the gates of the inputtransistors via resistors R1 and R2.

The input transistors, the inductors, and the variable capacitors 104Nand 104P amplify the capacitor divided RF input signals to producesamplified RF signals. The output capacitors provide the amplified RFsignals as the output of the power amplifier. Note that the capacitancelevel of the variable capacitors is set based on the operational basedcontrol signal 102.

As one of average skill in the art will appreciate, the power amplifier84 of FIG. 6 may be implemented with one, two, or three of the adjustmodules 100, 104, and 106. For instance, the variable capacitors 104Nand 104P may be omitted.

FIG. 7 is a schematic block diagram of yet another embodiment of anadjustable power amplifier 84. In this embodiment, the single-endedpower amplifier 84 includes a plurality of input transistors(T_(IN1)−T_(IN4)), input capacitor C_(IN), inductor L, the gain adjustmodule 100, a calibration module 105, the bias circuit 106, and outputcapacitor C_(OUT). As shown, the gain adjust module 100 includes aplurality of capacitors C1-C4 coupled in series with a plurality ofswitches S5-S8. The bias adjust circuit 106 includes a plurality ofcurrent sources CS1-CS4 coupled in series with a plurality of switchesS9-S12 to produce a bias voltage via transistor T₁. The calibrationmodule 105 includes a peak detectors 108 and 110, analog-to-digitalconverters 112 and 114, and an adjustment module 116.

In operation, the calibration adjust module 105 monitors the peak levelof the output of the power amplifier, the peak level of the input of thepower amplifier and the bias level of the input transistorsT_(IN1)-T_(TIN4). The calibration module 105 monitors the output of thepower amplifier (PA_(OUT)) via peak detector 108 to produce a peakvoltage. The peak output voltage is converted to a digital signal viathe analog-to-digital converter 112, which is provided to the adjustmentmodule 116. The adjustment module 116, which performs one or more of thefunctions of FIGS. 8-11, determines the operational based control signal102 by comparing the measured peak output power level with a desiredpeak output power level. Based on this comparison, the adjustment module116 generates the operational based control signal 102 to enable one ormore of switches 1-4 such that the desired output power level is moreclosely achieved.

The calibration module 105 monitors the input peak levels via peakdetector 110, which produces an analog peak signal value that isconverted to a digital value via the analog-to-digital converter 114.The adjustment module 116, performing one or more of the functions ofFIGS. 8-11, determines the operational base control signal 102 for thegain adjust module 100 by comparing the digital peak input voltage witha desired input peak voltage. In this embodiment, the operational basedcontrol signal 102 enables one or more of switches S5-S8 to adjust thevoltage level of the input RF signals.

The calibration module 105 further monitors the input bias level of theinput transistors via resistor R2. When the bias level is different thana desired bias level, the adjustment module 116 produces the operationalcontrol based signal 102 for the bias adjust circuit 106. In oneembodiment, the control signal 102 may enable one or more of switchesS9-S12.

As one of average skill in the art will appreciate, switches S1-S12 maybe implemented using transistors. As one of average skill in the artwill further appreciate, a differential implementation of a poweramplifier may be achieved by utilizing a mirror image of the circuit ofFIG. 7.

FIG. 8 is a logic diagram of a method for compensating a power amplifierbased on operational-based changes that begins at step 130 where acalibration module, which may be imbedded within one of the processingmodules 64 and 76, measures one of a plurality of operational parametersof the power amplifier to produce a measured operational parameter. Inone embodiment, the plurality of operational parameters includesgate-source voltage of at least one input transistor, peak input voltageof the power amplifier, and peak output voltage of the power amplifier.The method continues at step 132 the calibration module compares themeasured operational parameter with a corresponding one of a pluralityof desired operational parameter settings. This may be done as will befurther described in FIGS. 9-11.

The method continues at step 134 where the method branches depending onwhether the comparison was favorable. If the comparison is favorable,the method proceeds to step 140, where the method waits for a nextinterval of measurement. Note that the measurement intervals may beperiodic (e.g., every 1-10 seconds) or randomly (e.g., when thetransmitter is idle).

If the comparison at step 134 was not favorable, the method proceeds tostep 136 where the calibration module determines a difference betweenthe measured operational parameter and the corresponding one of aplurality of desired operational parameter settings. The method thenproceeds to step 138 where the calibration module calibrates the one ofthe plurality of operational settings based on the difference.

FIG. 9 is a logic diagram of a method for method for compensation apower amplifier based on a particular operational condition that beginsat step 150 where the calibration module measures temperature of anintegrated circuit containing the power amplifier to produce a measuredtemperature. The method continues at step 152 where the calibrationmodule equates the measured temperature to a desired gate-sourcevoltage. The method continues at step 154 where the calibration modulemeasures the gate-source voltage of an input transistor of the poweramplifier to produce a measured gate-source voltage. The methodcontinues at step 156 where the calibration module compares the measuredgate-source voltage with the desired gate-source voltage.

The method continues at step 158 where the method branches depending onwhether the comparison of step 156 was favorable. When comparison wasfavorable, the method continues at step 164 where the calibration modulewaits to take another measurement until the next interval. If thecomparison was unfavorable, the method continues at step 160 where thecalibration module determines a difference between the desiredgate-source voltage and the measured gate-source voltage. The methodcontinues at step 162 where the calibration module adjusts a biasvoltage level of the input transistor based on the difference betweenthe desired gate-source voltage and the measured gate-source voltage.

FIG. 10 is a logic diagram of a method for compensation a poweramplifier based on another particular operational condition. The methodbegins at step 170 where the calibration module measures a peak level ofan input voltage to the power amplifier to produce a measured peak inputlevel. The method continues at step 172 where the calibration modulecompares the measured peak input level with a desired peak input level.The method continues at step 174 where the method branches depending onwhether the comparison of step 172 was favorable. When the comparisonwas favorable, the method proceeds to step 180 where the calibrationmodule waits until the next interval to take another measurement.

When the comparison was unfavorable, the method continues at step 176where the calibration module determines a difference between themeasured peak input level and the desired peak input level. The methodcontinues at step 178 where the calibration module adjusts gain of thepower amplifier based on the difference between the measured peak inputlevel and the desired peak input level. The adjustment may be made byadjusting the capacitance of the gain adjust module 100 and/or thecapacitance of the gain adjust module 104.

FIG. 11 is a logic diagram of a method for compensation a poweramplifier based on yet another particular operational condition thatbegins at step 190 where the calibration module measures a peak level ofan output voltage to the power amplifier to produce a measured peakoutput level. The method continues at step 192 where the calibrationmodule compares the measured peak output level with a desired peakoutput level. The method continues at step 194 where the method branchesdepending on whether the comparison of step 12 was favorable. When thecomparison was favorable, the method proceeds to step 200 where thecalibration module waits until the next interval to take anothermeasurement.

When the comparison was unfavorable, the method continues at step 196where the calibration module determines a difference between themeasured peak input level and the desired peak input level. The methodcontinues at step 198 where the calibration module adjusts transmitpower of the power amplifier based on the difference between themeasured peak output level and the desired peak output level. This maybe done by enabling one or more of switches S1-S4 of FIG. 7.

As one of average skill in the art will appreciate, the term“substantially” or “approximately”, as may be used herein, provides anindustry-accepted tolerance to its corresponding term. Such anindustry-accepted tolerance ranges from less than one percent to twentypercent and corresponds to, but is not limited to, component values,integrated circuit process variations, temperature variations, rise andfall times, and/or thermal noise. As one of average skill in the artwill further appreciate, the term “operably coupled”, as may be usedherein, includes direct coupling and indirect coupling via anothercomponent, element, circuit, or module where, for indirect coupling, theintervening component, element, circuit, or module does not modify theinformation of a signal but may adjust its current level, voltage level,and/or power level. As one of average skill in the art will alsoappreciate, inferred coupling (i.e., where one element is coupled toanother element by inference) includes direct and indirect couplingbetween two elements in the same manner as “operably coupled”. As one ofaverage skill in the art will further appreciate, the term “comparesfavorably”, as may be used herein, indicates that a comparison betweentwo or more elements, items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1.

The preceding discussion has presented various embodiments of anadjustable power amplifier that can maintain linearity over varyingoperational conditions while reducing power consumption. As one ofaverage skill in the art, other embodiments may be derived from theteachings of the present invention without deviating from the scope ofthe claims.

1. A method for compensating a power amplifier based onoperational-based changes, the method comprises: measuring one of aplurality of operational parameters of the power amplifier to produce ameasured operational parameter; comparing the measured operationalparameter with a corresponding one of a plurality of desired operationalparameter settings; when the comparing of the measured operationalparameter with the corresponding one of a plurality of desiredoperational parameter settings is unfavorable, determining a differencebetween the measured operational parameter and the corresponding one ofa plurality of desired operational parameter settings; and calibratingthe one of the plurality of operational settings based on thedifference.
 2. The method of claim 1, wherein the plurality ofoperational parameters comprises: gate-source voltage, peak inputvoltage, and peak output voltage.
 3. The method of claim 2 furthercomprises: measuring temperature of an integrated circuit containing thepower amplifier to produce a measured temperature; equating the measuredtemperature to a desired gate-source voltage; measuring the gate-sourcevoltage of an input transistor of the power amplifier to produce ameasured gate-source voltage; comparing the measured gate-source voltagewith the desired gate-source voltage; when the comparing the measuredgate-source voltage with the desired gate-source voltage is unfavorable,determining a difference between the desired gate-source voltage and themeasured gate-source voltage; and adjusting a bias voltage level of theinput transistor based on the difference between the desired gate-sourcevoltage and the measured gate-source voltage.
 4. The method of claim 2further comprises: measuring a peak level of an input voltage to thepower amplifier to produce a measured peak input level; comparing themeasured peak input level with a desired peak input level; when thecomparing the measured peak input level with a desired peak input levelis unfavorable, determining a difference between the measured peak inputlevel and the desired peak input level; and adjusting gain of the poweramplifier based on the difference between the measured peak input leveland the desired peak input level.
 5. The method of claim 2 furthercomprises: measuring a peak level of an output voltage to the poweramplifier to produce a measured peak output level; comparing themeasured peak output level with a desired peak output level; when thecomparing the measured peak output level with a desired peak outputlevel is unfavorable, determining a difference between the measured peakinput level and the desired peak input level; and adjusting transmitpower of the power amplifier based on the difference between themeasured peak output level and the desired peak output level.
 6. Anadjustable power amplifier comprises: a power amplifier; and acalibration module coupled to: measure one of a plurality of operationalparameters of the power amplifier to produce a measured operationalparameter; compare the measured operational parameter with acorresponding one of a plurality of desired operational parametersettings; when the comparing of the measured operational parameter withthe corresponding one of a plurality of desired operational parametersettings is unfavorable, determine a difference between the measuredoperational parameter and the corresponding one of a plurality ofdesired operational parameter settings; and calibrate the one of theplurality of operational settings based on the difference.
 7. Theadjustable power amplifier of claim 6, wherein the plurality ofoperational parameters comprises: gate-source voltage, peak inputvoltage, and peak output voltage.
 8. The adjustable power amplifier ofclaim 7, wherein the calibration module further functions to: measuretemperature of an integrated circuit containing the power amplifier toproduce a measured temperature; equate the measured temperature to adesired gate-source voltage; measure the gate-source voltage of an inputtransistor of the power amplifier to produce a measured gate-sourcevoltage; compare the measured gate-source voltage with the desiredgate-source voltage; when the comparing the measured gate-source voltagewith the desired gate-source voltage is unfavorable, determine adifference between the desired gate-source voltage and the measuredgate-source voltage; and adjust a bias voltage level of the inputtransistor based on the difference between the desired gate-sourcevoltage and the measured gate-source voltage.
 9. The adjustable poweramplifier of claim 7, wherein the calibration module further functionsto: measure a peak level of an input voltage to the power amplifier toproduce a measured peak input level; compare the measured peak inputlevel with a desired peak input level; when the comparing the measuredpeak input level with a desired peak input level is unfavorable,determine a difference between the measured peak input level and thedesired peak input level; and adjust gain of the power amplifier basedon the difference between the measured peak input level and the desiredpeak input level.
 10. The adjustable power amplifier of claim 7, whereinthe calibration module further functions to: measure a peak level of anoutput voltage to the power amplifier to produce a measured peak outputlevel; compare the measured peak output level with a desired peak outputlevel; when the comparing the measured peak output level with a desiredpeak output level is unfavorable, determine a difference between themeasured peak input level and the desired peak input level; and adjusttransmit power of the power amplifier based on the difference betweenthe measured peak output level and the desired peak output level.
 11. Aradio comprises: a receiver section operably coupled to convert inboundradio frequency (RF) signals into inbound baseband signals; and atransmitter section operably coupled to convert outbound basebandsignals into outbound RF signals, wherein the transmitter sectionincludes: an adjustable power amplifier including: a power amplifier;and a calibration module coupled to: measure one of a plurality ofoperational parameters of the power amplifier to produce a measuredoperational parameter; compare the measured operational parameter with acorresponding one of a plurality of desired operational parametersettings; when the comparing of the measured operational parameter withthe corresponding one of a plurality of desired operational parametersettings is unfavorable, determine a difference between the measuredoperational parameter and the corresponding one of a plurality ofdesired operational parameter settings; and calibrate the one of theplurality of operational settings based on the difference.
 12. The radioof claim 11, wherein the plurality of operational parameters comprises:gate-source voltage, peak input voltage, and peak output voltage. 13.The radio of claim 12, wherein the calibration module further functionsto: measure temperature of an integrated circuit containing the poweramplifier to produce a measured temperature; equate the measuredtemperature to a desired gate-source voltage; measure the gate-sourcevoltage of an input transistor of the power amplifier to produce ameasured gate-source voltage; compare the measured gate-source voltagewith the desired gate-source voltage; when the comparing the measuredgate-source voltage with the desired gate-source voltage is unfavorable,determine a difference between the desired gate-source voltage and themeasured gate-source voltage; and adjust a bias voltage level of theinput transistor based on the difference between the desired gate-sourcevoltage and the measured gate-source voltage.
 14. The radio of claim 12,wherein the calibration module further functions to: measure a peaklevel of an input voltage to the power amplifier to produce a measuredpeak input level; compare the measured peak input level with a desiredpeak input level; when the comparing the measured peak input level witha desired peak input level is unfavorable, determine a differencebetween the measured peak input level and the desired peak input level;and adjust gain of the power amplifier based on the difference betweenthe measured peak input level and the desired peak input level.
 15. Theradio of claim 12, wherein the calibration module further functions to:measure a peak level of an output voltage to the power amplifier toproduce a measured peak output level; compare the measured peak outputlevel with a desired peak output level; when the comparing the measuredpeak output level with a desired peak output level is unfavorable,determine a difference between the measured peak input level and thedesired peak input level; and adjust transmit power of the poweramplifier based on the difference between the measured peak output leveland the desired peak output level.